High-speed continuous casting method

ABSTRACT

A high-speed continuous casting apparatus and method wherein the method includes partially solidifying a molten metal in a mold defined between the peripheral groove of a rotating casting wheel and a flexible band until the metal shrinks and draws away from the casting wheel, thereupon removing the band from the casting wheel and subsequently cooling the metal to complete its solidification. The apparatus includes the combination of a casting wheel having a peripheral groove with a portion of its length closed by an endless band to form a casting mold and an auxiliary cooling means for cooling the metal to complete its solidification. This allows the casting wheel to be rotated at that rotational speed which causes the metal to pass from the casting wheel as, or shortly before or after, the metal shrinks away from the casting wheel.

United States Patent [72] Inventors George E. Lenaeus Carrollton; Danlel B. Coler, Carrollton; John H. Murphy, Atlanta, all of Ga. [21] Appl. No. 821,299 [22] Filed May 2, 1969 [45] Patented Nov. 30, 1971 [73] Assignee Southwire Company Carrollton, Ga.

[54] HIGH-SPEED CONTINUOUS CASTING METHOD 4 Claims, 7 Drawing Figs.

[52] U.S. Cl 164/87, 164/89, 164/278 [51] Int. Cl 822d 11/06 [50] Field of Search 164/82, 87, 89, 278, 283

[56] References Cited UNITED STATES PATENTS 2,698,467 1/1955 Targuinee et a1. 164/283 X 3,080,627 3/1963 Hoteko 164/278 X 3,261,059 7/1966 Properzi 164/89 X 3,351,126 11/1967 Richards et al.... l64/282X 3,391,725 7/1968 Rossi 164/89 3,452,808 7/1969 Properzi 164/278 3,416,594 12/1968 Gyongyos 164/278 Primary Examiner-R. Spencer Annear Attorney-Jones & Thomas ABSTRACT: A high-speed continuous casting apparatus and method wherein the method includes partially solidifying a molten metal in a mold defined between the peripheral groove ofa rotating casting wheel and a flexible band until the metal shrinks and draws away from the casting wheel, thereupon removing the band from the casting wheel and subsequently cooling the metal to complete its solidification. The apparatus includes the combination of a casting wheel having a peripheral groove with a portion of its length closed by an endless band to form a casting mold and an auxiliary cooling means for cooling the metal to complete its solidification. This allows the casting wheel to be rotated at that rotational speed which causes the metal to pass from the casting wheel as, or shortly before or after, the metal shrinks away from the casting wheel.

BACKGROUND OF THE INVENTION The continuous casting of molten metal in a peripheral These and other features and advantages of the invention will be more clearly understood upon consideration of the following specification and accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevational view invention;

FIG. 2 is a cross-sectional view taken along line 2-2 in FIG.

of one embodiment of the FIG. 3 is a schematic representation of a prior art casting wheel illustrating the three solidification phases during the continuous casting of a molten metal;

FIG. 4 is a schematic representation of that embodiment of the invention shown in FIG. 1 showing the three solidification phases therein;

FIG. 5 is a side elevational view, similar to FIG. 1, but showing an alternate form of the invention;

FIG. 6 is a schematic representation of that embodiment of the invention shown in FIG. 5; and

FIG. 7 is a graph illustrating the relationship between the heat-transfer characteristics of a prior art casting wheel and of that embodiment of the invention shown in FIGS. 1 and 5.

These figures and the following detailed description disclose specific embodiments of the invention; however, it is to be understood that the invention may be embodied in other forms.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in more detail to the drawing, in which like numerals of reference illustrate like parts throughout the several views, FIG. 1, shows casting wheel 10 having an endless flexible band or support rolls 19 supported by frame 20 of the cooling section 18 and a plurality of manifolds 21 and 21'; the manifolds 21 being positioned above and below the path P of the metal through the cooling section 18 and the manifolds 21 positioned at the sides of the cooling section 18.

Support rolls incline of rolls in path P. Side guide walls 27 are positioned on opposite sides of path P and also serve to retain the metal in its path.

Upper rolls 26 are rotatably mounted in a frame 28 pivoted by the frame 20. The cylinder 32 has a suitable control circuit T to selectively extend and retract the rolls 26 as seen in FIG. 2. If it is desired to more positively drive the metal up the incline of path P with support rolls l9, cylinder 32 can be adjusted to move upper rolls 26 into engagement with the upper surface of the metal to urge the metal into more positive contact with support rolls 19.

The manifolds 21 and 21' are so positioned that all sides of metal C are cooled and each manifold 21 21' can be independently controlled through valves V1, V2, V3 and V4 to selectively control the cooling rate of each side of metal C. The cooling fluid is discharged on metal C through a plurality of conventional nozzles 35.

As metal C exits the cooling section 18, it passes to a rolling mill (not shown) or other subsequent processing equipment. If desired, the metal can be received between a pair of pinch rolls 36 of conventional design to assist its movement.

As is best shown in FIGS. 5 and 6, an alternate embodiment of the invention is provided which includes casting wheel 40, flexible band 41, and band support wheels 42, 44, and 45. Pouring pot 46 is arranged to pour molten metal into the peripheral groove of casting wheel 40. The arrangement of casting wheel 40, band supports wheels 42-45 and pouring pot 46 is similar to the arrangement of FIG. 1; however, the extended cooling section 18 of FIG. I is replaced by water spray manifold 48, and the cast bar C is allowed to remain in the casting wheel until it is extracted therefrom at the conventional position. Water spray manifold 48 is arcuate and extends around the casting wheel from the position where band 41 is removed from the peripheral groove of the casting wheel by support wheel 45, to the point of extraction of the cast bar C. Water spray manifold 48 functions to spray water or some other coolant directly onto the surface of cast bar C as the cast bar approaches the point of extraction from casting wheel 40. The cast bar is guided between pinch rolls 49 after it has been extracted from casting wheel 40, and is subsequently guided to a rolling mill, or the like for further processing. Thus, the band arrangement shown in FIG. 5 is similar to the arrangement of FIG. 1, but the partially solidified cast bar emerging from band 41 is allowed to remain in the casting wheel as it is further directly cooled by the water spray.

OPERATION In operation it will be seen that casting is started in both embodiments of the invention by starting the rotation of the casting wheel, the band support wheels and the flexible band in the known manner. The molten metal is then introduced into the casting mold M from the pouring pot whereupon the metal is cooled in the mold M by spraying the outside of the mold M from conventional spray assemblies S as seen in FIGS. l and 5. As the molten metal moves with the mold M, it is cooled sufiiciently during its first solidification phase to start partial solidification of the metal. This forms a crust of the metal adjacent the sides of the mold M while the metal in the center of the mold M is still unsolidified. This is best seen by reference to FIGS. 4 and 6 wherein the mold M and the solidifying metal are shown schematically.

This crust continues to thicken during the second solidification phase and the rotational speed of the casting wheel is such that by the time the metal has reached the end of phase 2, the crust enclosing the molten center is sufficiently thick to support the molten center without collapsing.

As illustrated in the embodiment of FIGS. 1, 2, and 4, the metal is discharged from the casting wheel 10 at or near the beginning of its third solidification phase, and is supported by the band I 1 until it reaches support rolls 19 in cooling section 18. Upon entering the cooling section 18, metal C is transported over support rolls 19 to the pinch rolls 36. The manifolds 21 and 21 spray a conventional coolant between the support rolls and upper rolls and through the opening in guide walls 27 onto the outside of meta! C to finish the solidification thereof while metal C is within the cooling section 18.

When the first portion of meta! C is discharged from the casting wheel 10 during startup of the casting operation, upper rolls 26 are lowered to a position above the upper surface of metal C by the cylinder 32 to insure that support rolls l9 guide metal C upwardly along the cooling section 18 until it passes through the pinch rolls 36. The casting process continues until the flow of molten metal into the casting mold M from the pouring pot 16 is stopped.

Referring to FIG. 3 of the drawings, it will be seen that in a conventional casting wheel 10', the molten metal is poured into the mold M in the casting wheel 10'. Immediately after entering the mold M, the metal is cooled during its first phase of solidification by the transfer of heat from the metal to the mold M. Subsequently, the metal cools in its second phase of solidification with a thin crust but with the metal still in substantially complete direct contact with the mold M.

When the crust of solidified metal becomes sufficiently thick, metal draws away from the mold M and the solidification of the metal enters its third phase. However, in the mold M during the third phase, the gap G formed between the mold M and the metal C' greatly reduces the rate at which heat is transferred from the metal C to the mold M. This is shown by the graph of FIG. 7 wherein the rate of heat transfer to the mold M during the solidification of the metal in the mold M of a prior art casting wheel 10' is indicated by a dashed line. The greatly reduced cooling rate during the third phase of solidification characteristic of the mold M limits the maximum speed of the casting wheel 10 to that speed which insures that complete solidification of metal C takes place while metal C is positioned within the mold M of the casting wheel 10'.

Referring to FIG. 4, the solidification phases of a metal being cast by the invention are illustrated schematically, showing that the metal is removed from the casting wheel 10 when the forming of the outer crust has reached that point at which the metal has shrunk and drawn away from the mold M. This point is or near the start of the third solidification phase and metal C still has a liquid core as indicated in FIG. 4 when it is discharged from the casting wheel 10. However, it will be seen that any conventional coolant may be passed over metal C to complete the solidification thereof at a much faster rate of heat transfer than any rate possible in the third phase in the conventional casting wheel 10' illustrated in FIG. 3.

The rate of heat transfer or cooling in the third phase of solidification by the invention relative cooling in the mold M can be best seen by referring to FIG. 7 wherein the solid line indicates that the rate of heat transfer by the invention in the third phase is much higher than that of a conventional casting wheel 10' as shown by the dashed line. Thus, it will now be understood that the invention requires the operation of the casting machine C at a rotational speed which will result in the metal passing to the cooling section 18 at the beginning of or early in the third solidification phase. It will also be understood that this requirement provides greater casting rates than were possible with prior art casting wheels. It will be further understood that although the cooling section 18 sprays a coolant onto metal C, other types of cooling may be utilized such as passing metal C through a tank filled with a coolant to cool the metal C.

As illustrated in the embodiment of FIGS. 5 and 6, the partially solidified bar can remain in the casting wheel during the third phase of solidification. When flexible band 41 is removed from the periphery of the casting wheel, the partially solidified cast bar is exposed, and coolant is sprayed from manifold 48 directly onto the outer surface of the cast bar. This direct cooling is generally similar to the direct cooling which results in the embodiment of the invention shown in FIGS. 1, 2, and 4, except that the cast bar is completely solidified before it is extracted from the casting wheel.

While the general concept of the invention includes directly cooling a partially solidified cast bar, the first embodiment of the invention shown in FIGS. 1, 2, and 4 provides extracting the partially solidified bar from the casting wheel and completely solidified.

The first embodiment of the invention allows phase three of the coo ing phases to be stretched out over an extended In order that the disadvantage of holding the bar in the casting wheel of the second embodiment of the invention be overthe casting machine.

In the first embodiment of the invention, the molten metal is poured into the arcuate cavities appearing in the cast bar.

Although specific embodiments of disclosed herein in the invention have been illustrating the invention, it is understood cooling the metal in the mold until the metal has partially removing the metal from the mold as an only partially moving the metal with the flexible peripheral groove along the upwardly inclined tangent so that the metal is supported by the flexible band,

guiding the flexible band downwardly away from the metal while continuing to move the metal along the upwardly inclined tangent, and

applying cooling fluid directly to the metal as the metal moves along the upwardly inclined tangent in sufficient quantity to complete the solidification of the metal before it reaches the level at which it was fed in a molten state into the mold.

2. In a metal casting process, the steps of:

engaging the peripheral groove of a rotating casting wheel with a continuous flexible band to fonn a mold,

in a molten condition into the mold,

solidified,

ing wheel,

continuing to pass the exposed partially solidified metal around the casting wheel in the peripheral groove so that the metal is continuously supported by the groove of the casting wheel,

applying coolant directly to the exposed surfaces of the parthe casting wheel, and removing the metal from the ing casting wheel after the solidified. 3. In a continuous casting process for casting metal wherein the metal in a molten condition peripheral groove of the rotatmetal has become substantially was poured in a molten state into the mold.

4. In a casting process, the steps of: engaging the peripheral groove of a rotating casting wheel with a continuous flexible band to fonn an arcuate mold, feeding metal in a molten condition into the mold,

' in the mold until the metal has red metal to complete the metal moves through the upwardly inclined tangent and before the metal reaches the level at which it was poured in a molten condition into the mold. 

1. In a metal casting process the steps of: engaging the peripheral groove of a rotating casting wheel with a continuous flexible band to form an arcuate mold, feeding metal in a molten condition into the mold, cooling the metal in the mold until the metal has partially solidified, guiding the flexible band away from the peripheral groove in an upwardly inclined tangent from the lower portion of the casting wheel, removing the metal from the mold as an only partially solidified metal and moving the metal with the flexible band away from the peripheral groove along the upwardly inclined tangent so that the metal is supported by the flexible band, guiding the flexible band downwardly away from the metal while continuing to move the metal along the upwardly inclined tangent, and applying cooling fluid directly to the metal as the metal moves along the upwardly inclined tangent in sufficient quantity to complete the solidification of the metal before it reaches the level at which it was fed in a molten state into the mold.
 2. In a metal casting process, the steps of: engaging the peripheral groove of a rotating casting wheel with a continuous flexible band to form a mold, feeding metal in a molten conditioN into the mold, cooling the metal in the mold as the metal passes around the casting wheel until the metal has at least partially solidified, guiding the flexible band generally tangentially away from the casting wheel to open the mold and to expose the partially solidified metal in the peripheral groove of the casting wheel, continuing to pass the exposed partially solidified metal around the casting wheel in the peripheral groove so that the metal is continuously supported by the groove of the casting wheel, applying coolant directly to the exposed surfaces of the partially solidified metal to complete the solidification thereof as the metal remains in the peripheral groove of the casting wheel, and removing the metal from the peripheral groove of the rotating casting wheel after the metal has become substantially solidified.
 3. In a continuous casting process for casting metal wherein the metal in a molten condition is poured into an arcuate channel defined by a peripheral groove of a rotatable casting wheel and an endless band extending about a portion of the peripheral groove, the improvement therein of guiding the band tangentially away from the vicinity of the peripheral groove of the casting wheel at a position about the casting wheel when the outer portion of the metal has solidified but before the inner portion of the metal has solidified to open the peripheral groove of the casting wheel, and continuously supporting the partially solidified metal and applying a fluid coolant directly to the metal so that the inner portion of the metal has completely solidified before it reaches the level at which it was poured in a molten state into the mold.
 4. In a casting process, the steps of: engaging the peripheral groove of a rotating casting wheel with a continuous flexible band to form an arcuate mold, feeding metal in a molten condition into the mold, cooling the molten metal in the mold until the metal has partially solidified, guiding the flexible band along an upwardly inclined tangent away from the peripheral groove at the lower portion of the casting wheel, removing the metal from the lower portion of the mold as an only partially solidified metal and moving the metal with the flexible band along the upwardly inclined tangent so that the metal is supported by the flexible band, gripping the metal along the upwardly inclined tangent with rotating rollers and moving the partially solidified metal with the rollers along the upwardly inclined tangent, and cooling the partially solidified metal to complete the solidification thereof as the metal moves through the upwardly inclined tangent and before the metal reaches the level at which it was poured in a molten condition into the mold. 